The statements in this section merely provide background information related to the present disclosure and may not constitute the prior art.
Moving Picture Experts Group (MPEG) and Video Coding Experts Group (VCEG) have developed an improved and excellent video compression technology over existing MPEG-4 Part 2 and H.263 standards. The new standard is named H.264/AVC (Advanced Video Coding) and was released simultaneously as MPEG-4 Part 10 AVC and ITU-T Recommendation H.264.
In H.264/AVC (hereinafter referred to as ‘H.264’), in order to interpolate a reference frame used in the inter prediction, a reference frame interpolated with ¼ fractional pixel precision is generated using a 6-tap filter and an average value filter. More specifically, the 6-tap filter is used so as to generate the ½ fractional pixel and the average value filter is used so as to generate the ¼ fractional pixel.
As described above, when the inter prediction is performed based on H.264, a motion is predicted and compensated with the ¼ fractional pixel precision by using the reference frame interpolated in the fractional pixel precision, so that it is possible to obtain the higher compression efficiency than the conventional method which uses only the reference frame having the integer pixel precision.
However, in the conventional compression technology, such as the aforementioned H.264, the reference frame is interpolated using only a fixed filter. Therefore, there is a problem in that when an image with a brightness change according to a time, such as lighting change, fade-in, or fade-out, is encoded, the change of a brightness signal is not taken into consideration, so that it fails to effectively predict the motion.